172 Mr. J. O. Westwood's Observations 



does not at all correspond with Mr. Sells's figure of one of his 

 nests, and leads us to conclude either that some inaccuracy exists 

 in Brown's observations, or that Mr. Sells's insect is not speci- 

 fically identical with Brown's, or else that the species occasion- 

 ally forms two valves to its nest, as indeed the observations both 

 of Mr. Sells and Mr. Saunders seem to prove is the case. La- 

 treille also described a nest which he had received from Jamaica, 

 (forwarded by an Englishman, Mr. With, to M. Royer, see 

 " Cours d'Entomologie," p. 508), with a single valve, as identical 

 with Brown's species, noticing at the same time the difference 

 between it and the description and figure of Brown (Latr. Vues 

 generales sur les Araneides a quatre pneumo-branchies, in Nouv. 

 Ann. du Museum, t. 1). The Baron Walckenaer, however, ques- 

 tions whether the single-valved nest be that of Brown's spider, 

 observing, " il est permis de croire que Latreille a decrit le nid 

 d'une espece de Mygale mineuse differente de celle de Brown, et 

 qui est peut-6tre le meme que celle qui au rapport d'Olivier, a 

 ete observee a la Guadaloupe par M. Badier," who considered 

 his nest from that island as identical with that of Latreille, al- 

 though it was described as having two valves, which were not 

 " opposees mais superposees, et ont une charniere commune ; la 

 plus grosse et la plus large est soudee dans la moietie de la partie 

 posterieure de I'autre et doit la recouvrir ainsi que les margelles 

 du trou." — (Hist. Nat. Ins. Apt. 1, 234.) 



It thus appears questionable, whether there are not two species 

 of American trap-door spiders, which differ in the mode of form- 

 ing the valves of their nests.* 



Let us now endeavour to trace the nomenclature of the Trans- 

 atlantic species. 



Linnaeus proposed the name of A. venatoria for a spider far too 

 concisely described, referring, as above mentioned, to Brown's 

 forty-fourth plate, but to the second figure on that plate, whereas 

 the nest with the double trap is figure 3, Sa, 3b, on the same 

 plate, to which Linnaeus has nowhere referred ; neither has Lin- 

 naeus described any spider under the name of A. nidulans, as 

 quoted by Latreille in his Memoir on Mygale above referred to. 

 We find this last name first and for the only time employed by 

 Fabricius, in the " Mantissa Insectorum" (vol. i. p. 3^3), as the 

 name of a spider in the collection of Sir J. Banks, from the 

 American islands, and to which description he added a reference 



* It may be mentioned ia connexion wilh this observation, that there are 

 several distinct American species now known, belonging to the same genus as 

 Mr. Sells's Jamaica spider. 



